The Senate has narrowly rejected an effort to scrap tough limits on mercury emitted from power plants. The Obama administration has trumpeted the rules affecting coal-burning power plants as an environmental triumph. But to industry groups, and many Republicans, these rules are the latest salvo in a war against coal. NPR's Tamara Keith reports.

TAMARA KEITH, BYLINE: This utility rule was a long time in coming, a very long time. Limiting pollution from power plants was written into the 1990 Clean Air Act and left to the EPA to flesh out into regulations. Many delays and a big court ruling later, in December, the agency announced the new standards.

PRESIDENT BARACK OBAMA: Today, my administration is saying enough.

KEITH: President Obama celebrated in an online video.

OBAMA: We estimate we'll prevent thousands of premature deaths, heart attacks and thousands of cases of asthma in children each year by 2016. So this is a good day. It's a good day in the fight for cleaner air.

KEITH: Old dirty power plants would have to install scrubbers or other technology to capture air pollution containing mercury and other dangerous substances. Environmental groups cheered. But for many on the right, this was just the latest example of administrative overreach. Here's Alaska Republican Lisa Murkowski earlier today on the Senate floor.

SENATOR LISA MURKOWSKI: Today's EPA too often seems to impose requirements that go beyond what is authorized or needed.

KEITH: And Texas Republican John Cornyn.

SENATOR JOHN CORNYN: This administration, unfortunately, is using the EPA to destroy a major source of reliable, affordable baseload electricity that we sorely need.

KEITH: As you can tell, this environmental rule became highly politicized, with Republicans led by Oklahoma's James Inhofe moving to repeal the EPA rule. That's what today's vote was about. Leading up to it, there's been an onslaught of lobbying from every angle, even ad campaigns.

KEITH: The ad is part of a million-dollar campaign on the issue from a brand-new limited government advocacy group, called American Commitment. Phil Kerpen is the group's president.

PHIL KERPEN: When you have an opportunity to put the elected officials on the record, I think it's very important to make sure there's awareness and engagement.

KEITH: Tennessee Republican Lamar Alexander wasn't persuaded. He was one of five Republicans who ultimately voted to defend the rule.

SENATOR LAMAR ALEXANDER: I would agree that the EPA has become a happy hunting ground for goofy regulations. But the late William F. Buckley once said that even a stopped clock is right twice a day.

KEITH: Alexander said he hoped this rule would mean someday soon visitor won't even think of calling the Great Smokey Mountains in his state the great Smoggy Mountains. Five Democrats and most of Alexander's Republican colleagues voted to repeal the rule, persuaded by arguments like those voiced by John Cornyn.

CORNYN: While this rule claims to be about public safety, it is a job-killing, ideologically driven attempt to cripple the coal industry in the United States.

KEITH: Advocates for repeal cite a study saying the rules would hurt power plants, raise utility rates and cost more than 100,000 jobs. The EPA's own analysis says jobs would actually be added in construction.

John Walke is the clean air director at the Natural Resources Defense Council. He's pleased with the outcome, though wishes it hadn't been so close.

JOHN WALKE: These are brain poisons and carcinogens. And yet, we saw a really irresponsible number of senators today vote to overturn these landmark health safeguards for the American people.

KEITH: The focus now of industry groups and their supporters is to delay implementation of the new rule. Tamara Keith, NPR News, the Capitol. Transcript provided by NPR, Copyright NPR.